Pheromone Follies

Just a dab of Realm or Desire 22 will make you sexually irresistible--or so say ads for these popular, alleged human sex pheromones. The latest research throws some cold water on their claims. Neurobiologists at Massachusetts General Hospital and Harvard University recently reported that a mutated gene in humans may render our ancestral pheromone detector useless.

In many mammals, pheromones are sniffed out by the vomeronasal organ, two small pits or tubes behind the nostrils. Some mice are so dependent on this sixth sense that they become sexually dysfunctional if the organ is removed. Despite keen interest from scientists and would-be Romeos, nobody has pinpointed a human pheromone. Moreover, the vomeronasal organ in humans shrinks during fetal development, and by birth may contain no nerve cells.

Emily Liman of Massachusetts General Hospital makes an even stronger case that people don't respond to pheromones the way other animals do. In rats, wafting pheromones cause chemical receptors to open tiny pores called ion channels, which send nerve signals to the brain. Liman and her colleagues believe they've identified the gene for these pheromone ion channels. But the equivalent gene in humans is mutated and nonfunctional, they found. If humans respond to pheromones, "they'd probably have to do so through different mechanisms than most other mammals," says Liman.